Ha, J. C., Robinette, R. L., & Davis, A. (2000). Survival and reproduction in the first two years following a large-scale primate colony move and social reorganization: American Journal of Primatology Vol 50(2) Feb 2000, 131-138.

Johnstone-Scott, R. A. (1998). The effects of a change in leadership in a breeding group of western lowland gorillas Gorilla g. gorilla at the Jersey Wildlife Preservation Trust: Dodo: Journal of the Wildlife Preservation Trusts Vol 34 1998, 42-65.

Lukas, K. E. (1999). The role of feeding motivation and individual differences in the development and maintenance of regurgitation and reingestion (r/r) in captive lowland gorillas. (gorilla gorilla gorilla) (primates). Dissertation Abstracts International: Section B: The Sciences and Engineering.

Tonooka, R., Tomonaga, M., & Matsuzawa, T. (1997). Acquisition and transmission of tool making and use for drinking juice in a group of captive chimpanzees (Pan troglodytes): Japanese Psychological Research Vol 39(3) Sep 1997, 253-265.